Apparatus for loading sheath wire heating units



April 13, 1943. J. L. ANDREWS APPARATUS FOR LOADING SHEATH WIRE HEATING UNITS Filed July 25; 1940' 5 Sheets-Sheet 1 6. AW Attorneg.

Inventor": John Lewxs Andrews,

April 13, 1943. J ANDREWS APPARATUS FOR LOADING SHEATH WIRE HEATING UNITS 5 Sheets-Sheet 2 Filed July 25, 1940 lnverftor: John Lewis Andrews,

His Attorneg.

A ril 13, 1943. J. L. ANDREWS 2,316,659

APPARATUS FOR LOADING SHEATH WIRE HEATING UNITS WWW 4 'IIIIIIIJIIIIII;

III!!! 54 \nven'to John Lewis Andrews,

' M W His Attorney.

'April 13,1943. J L, ANDREWS APPARATUS FOR LOADING SHEATH WIRE HEATING UNITS I Filed July 25, 1940 5 Sheets-Sheet 4 \TWV8TTtOT: John Lewis Andrews,

3 N 6. His Attorneg.

A ril 13,1943. J. 1.. ANDREWS APPARATUS FOR LOADING SHEATH WIRE HEATING UNITS Filed July 25, 1940 5 Sheets-Sheet 5 Attorney.

. w e L m n a Vn P L n h 0 J ..lllllllrulllllkllllllll Patented Apr. 13, 1943 UNITED STATES PATENT OFFICE- APPARATUS FOR LOADING SHEATH WIRE I HEATING UNITS John Lewis Andrews, Elmwood Park, Ill., assignor to Edison General Electric Appliance Company, Inc., Chicago, 111., a corporation of New York ' Application July 25, 1940, Serial No. 347,446 1 21 Claims.

electric heating units wherein a helical resistance conductor is encased by a sheath and is embedded in and held in spaced relation with the sheath by means of an electrically insulating, heat refractory and heat conducting material, such as powdered magnesium oxide. Qne heating unit of this character is described in the United States patent to Charles C. Abbott No.

1,367,341, dated February 1, 1921.

This invention contemplates the provision of improved apparatus for loading the sheath of the heater with the insulating material so as to embed the resistance conductor and hold it in spaced relation with reference to the sheath, in a simple, reliable and efiicient manner.

In accordance with this invention, suitable means are. provided for holding the sheath in a substantially upright position, and also for holding the terminals of the resistance element, which are connected to the ends of the element,

in proper relation to the sheath, generally in the vertical center line of the sheath. Suitable means is provided for feeding to the sheath the powdered magnesium oxide at a-regulate'd rate.

ATsuitable vibratory device is, provided for im parting to the sheath intermittent impacting blows to settle the insulation within the sheath while it is being filled. A suitable centering device is arranged to be inserted in the sheath to hold the portions of the coiled resistance element between the terminals in the center line of the sheath while the sheath is being loaded.

Means are provided for effecting an up and down movement of the centering device in the sheath as the insulating material is being fed to the sheath. And-the centering device is constructed and arranged so that each time it is lowered it engages the top surface of the insulating material so as to displace the insulating material upwardly around the coiled resistance element in order to elevate slightly the turns of the conductor and thereby compensate for sagging of .the wound resistance elementdue to its own weight and the weight of the settling insulating material.

The means are provided for reciprocating the centralizer including means for temporarily releasing the centralizer from the driving force when the centralizer engages the top surface'of the insulating material, and also for progressively elevating it so that the lower limit of each downward stroke of the centralizer is at a higher level in the sheath than that of the previous stroke.

Moreover, the means for feeding the insulating material to'the sheath is controlled to reduce the flow of insulating material as the level of the insulating material approaches the upper end of the sheath so that the density of the insulating material at the upper. end of the sheath is substantially the same as that of the insulating material throughout the remainder of the sheath.- Moreover, the control of the flow of insulating material is such that it is stopped at precisely a predetermined high level in the sheath.

. The entire apparatus is under the control of a single manually operable control lever which when operated to a predetermined positionstarts the loading operation. Furthermore, the apparatus automatically stops itself when the loading operation has been completed.

For a more complete understanding of this invention, reference should be had to the accompanying drawings in which Fig. 1 is a fragmentary front elevation of loading apparatus arranged in accordance with this invention; Fig. 2 is a fragmentary side elevation of the apparatus of Fig. 1; Fig. 3 is a fragmentary front elevation similar to Fig. 1, but illustrating certain parts of the apparatus in different operative positions than they occupy in Figs. 1 and 2; Fig. 4 is an enlarged fragmentary front elevation of the upper portion of the loading apparatus of 1-3; Fig. 5 is a fragmentary side elevation of the parts of the apparatus shown in Fig. 4, parts being shown in section so as to illustrate certain details of construction; Figs. 6, 7 and 8 are sectional views taken through the lines 6-6, 'l'l, 8-8 respectively of Fig. 4 and looking in the directions of the arrows associated with these lines; Fig. 9 is an enlarged fragmentary front elevation of the middle portion of the loading apparatus of Figs. 1-3; Figs. 10, 11, 12 and. 13 are sectional views taken through the lines Ill-I0, ll--I|, lZ-IZ and I3|3 respectively of Fig. 9 and looking in the directions of the arrows associated with these lines; Fig. 14 is a still larger fragmentary front elevation illustrating certain parts of the loading apparatus; Figs. 15, 16,17 and 18 are sectional views taken through the lines l5--l5, lG-IG, I'|-|'l and 18-48 respectively of Fig. 14 and looking in the direction of the arrows associated with these lines; Fig. 19 is an enlarged elevation in section illustrating type has been Referring to the drawings, this invention has been illustrated in one form as'appliedito appasheathed type, such as described in the abovementioned Abbott patent. A heating unit oI-this illustrated in Fig. 21; this unit comprises a helical resistance element It encased by a metallic sheath ll. Suitable terminals l2 are mechanically and electrically connected to the ends of the resistance conductor Ill. For'this purpose, the resistance conductor is threaded on the terminals, as shown, and as fully described in United States Patent No. 1,494,938 to'C. C, Abbott, dated May 30, 1924. The resistance cond'uctor I is embedded in and is held in spaced relation with reference to the sheath H by a highly compacted mass l3 of heat refractory, heat conducting, electrically insulatingmaterial, such as powdered magnesium oxide. The powdered magnesium oxide is compressed into a dense compact mass in any suitable way asby reducing and elongating the sheath. The mass of insulating material l3 functions to hold the resistance element In in spaced relation with reenforced by a ratus for loading electric heating units of the a by means of rivets 23a (Figs. ll and 10). The

plates l1 and '28 aresecured to the bracket 23 by the screw-fastening means "23, (Figs. 1, 3, 9 and 10). I

Mounted a suitable standard 28 for supporting the heater sheath u (Figs. 1 and 2). The standard a is providedfwith ahead 29 having in general the shape 0! amushroom, and provided with an upright cylindrical extension 33 whichis arranged k to be inserted in the lower end of the sheath, as

clearly shown in Fig. 19.

It is to be understood that the terminal I2 at the lower end of the sheath is supported in its central position with reference to the sheath by means of a suitable head 3! which is rigidly secured to the lower end of the terminal or which may be assembled on theterminal and held by means of a small head on the terminal and which is received in a recess 32 provided for it in the lower end .of the sheath. This head or washer reference to the sheath, preferably so that'its 9 axis coincides with the axis of the sheath, and it also functions to conduct heat from the resistance element ID to the sheath. The inner ends of the terminals I2 are also embedded in the powdered insulating material l3, as shown, and are insulated from the sheath H and held in spaced relation with it by means of the insulating material.

The apparatus for loading the sheath comprises a suitable frame-work M which comprises upright channel-shaped columns l5 which are arranged in spaced-apart parallel relationship, as shown in Figs. 1, 3 and 9. The columns at the bottom are provided with feet l6 which rest upon the floor or any other suitable supporting base. Secured to the upper ends of the columns I5 is a vertically positioned plate-like member II. This plate is provided at its edges with forwardly extending sections l8 which terminate at the 'front in inwardly extending flanges or webs IS.

The forwardly extending sections l8 are rigidly secured to the upper ends of the columns l5. For this purpose, the columns l5 are provided with extensions 20 (Figs. 1, 2, 3 and 9) which are secured to the sections l8 in any suitable manner, as by bolts 2! (Fig. 9). The flanges i9, as shown in Figs. 1, 3 and 9, terminate a considerable distance above the lower end of the plate l1. Also, it will be observed in Figs. 6, 8, l2 and '13 that the sections iii of that part of the plate I! below the flanges iii are considerably shallower than are the corresponding parts of the plate that are coextensive with the flanges IS. The frame-work I4 is secured to a fixed pair of brackets 22 and 23 which may be supported by any suitable means (not shown). For this purpose, the plate I! is rigidly secured to the bracket 22 by a screw-fastening means 24 and dowels 2412 (Figs. 1, 3, 4 and 5). Interposed between the bracket 22 and the plate i1 is a spacing plate 22a. At the lower end the plate I1 is 3| in addition to holding the terminal I2 centrally of the sheath,function's to close the lower end of the sheath. The cylindrical extension 30 on the support 23 is received in the recess 32 to center and hold the lower end of the sheath against lateral displacement.

It will be further understood that before the heater sheath ll, resistance conductor l0 and terminals H are insertedin the loading apparatus, the resistance conductor will have been secured to the upper and lower terminals and they will have been threaded through the sheath so as to bringthe head 3| on the lower terminal l2 into its recess 32.

The upper terminal I2, instead of being provided with an enlarged head like the lower terminal, is provided'with a relatively small head 33; The head 33 is supported by a terminal rod 34. The terminal rod 34 at its lower end. is provided with a hook 35 which is provided with a jaw 35a that engages the head and therebyretains the upper'terminal I2 and the resistance conductor l0 under tension, as shown in Fig. 19. The hook is provided with an enlarged opening above the jaw, as shown, through which the enlarged head 33 may be inserted and then dropped down to engage the jaw which supports the terminal l2. The rod 34 functions to support the terminal 12 in its elevated position. The rod 34 extends on up to a point adjacent the top of the apparatus where it is secured to an arm 36. The arm 36 is supported by means of a rod 31 which extends down back of the plate I! and is secured to a lever 38 which is pivoted to the plate I! by means of a pin 38a (Figs. 4, 5 and 8). Mounted upon the rod 31 is a compression spring 39 which has its lower end abutting against a ber 4| is secured to anangle member 42 which in turn is rigidly secured to the upper end of the plate l1. A suitable latch 43 controls the position of the lever 38 and holds the lever against clockwise movement, the force ofv which is imparted to the lever as viewed in Figs. 1, 3 and 4, by the compression spring 39. The latch 43 is provided with two seats or detents 43a and 43b to hold the lever 38 in each of two positions, in

one of which it is shown in Figs. 1 and 4 and in the other of which it is shown in Fig. 3; The latch 43 is mounted upon a fixed pivot 43c (Figs.

relatively heavy plateflwluch in the lower part of the apparatus is v 4, and 8), and it is biased in a latching direction, that is. in a counter-clockwise direction, as viewed in Fig. 4 by means of a tension spring 43d anchored to a fixed pin 43e. Attached to the lever 38 is a rod 44 whereby the'lever may be moved in the counter-clockwise direction. This rod is provided with a hooked portion 44a which engages one end of lever 38 and with an eyelet portion 44b for manual operation of the lever 38.

Arranged to operate in the sheath around the resistance conductor l9 and its terminals I2 is a centralizing member 45 (Figs. 14, 15, 19 and 20). The centralizing member, as shown, is cylindrical in form and is provided with a series of vertically arranged ribs 46 on the outside spaced circumierentially about the centralizer, and which are arranged to engage the inner wall of the sheath I. as shown in Figs. 19 and 20. It will be understood that a running clearance will be provided between these ribs and the sheath. The centralizer also has a central aperture 41 which fits about the helical coil I8. In this way the centralizer as it rises maintains the central axis of the coil substantially coincident with the axis of the sheath. The lower end of the centralizer is provided with a flat wall, and also with a second wall 410 which inclines upwardly and inwardly from the fiat wall toward the central axis of the centralizer, all as clearly shown.

The centralizer 45 is threaded upon the lower end of a centralizing tube 48 which surrounds the rod and extends upwardly to a point adjacent the top of the apparatus where it is secured to a transverse bridge member 49. The member 49 carries a split nut 50 which receives the tube 48 and which is rigidly clamped to it, as shown in Fig. 4, The member 49 is provided in its opposite ends with slots 5| which receive the flangelike sections IS on the plate l1. This establishes a sliding connection between the bridge 49 and the plate H. The bridge 49 is rigidly secured to a carriage 52, the construction of which is shown more clearly in Fig. 12. As there shown, the carriage 52 is provided with slots 53 which are received by the forward flanges of the upright columns l5, whereby the carriage may he slid up and down on these columns. A pair of parallel rods 54.function to connect the carriage 52 with the bridge 49. These rods at their upper ends are rigidly secured to the bridge by means of nuts 55, and at their lower ends are provided .with laterally-extending webs or feet 56 (Figs.

9 and 12). which are rigidly secured to the carriage 52 by means of bolts 51. The carriage 52 is provided with a knob or handle 58 whereby the carriage and hence the bridge and centralizing tube 48 connected with it can be conveniently depressed by the operator, at the proper time.

Secured to the bridge 49 is a wedge cam 59 (Figs. 1, 4 and 5) which is rigidly connected to a transverse plate 60 that is substantially parallel to the bridge '49 and which is attached to the bridge by means of a pair of bolts 6|. The bolts 6| are loosely arranged in the plates 49 and 60 ,so that these plates can be moved relative to each other for a limited distance, as determined by the length of the space between the heads of the bolts and their nuts. In Figs. 1,4 and 5 the plates are shown at their maximum distance apart. The wedge cam 59 is arranged to be gripped by a pair of rollers 62 provided on the lower ends of lever arms 63 which are pivoted intermediate their ends to the plate 4|. The upper ends of the levers 63 are biased apart by means of a compression spring 64. This spring 64 is mounted upon a rod that issecured at its right-hand end, as viewed in Fig. 5, to a block 66 pivoted to the upper end of the right-hand lever 83, and which has its opposite and freely slidably in a block 61 pivotally mounted on the upper end of the left-hand lever 63. The rod 85 carries an abutment 68 in the form of a pair of nuts threaded on the rod, as shown in Fig. 5. The compression spring 64 is interposed between the block 61 and the abutment 68 so as to bias the upper ends of the levers apart and thereby force the roller 62 inwardly with relation to the cam 59. This cam 59 when engaged by the rollers 62 will hold the centralizing tube 48, the bridge 49 and the carriage 52 in their upper operative positions.

Also mounted on the bridge 49 is a roller 680 which when the carriage 52 is depressed by the knob 58 is moved downwardly to operate the latch 43 from its position of Figs. 1 and 4 to its position of Fig. 3 under certain conditions of operation, as will be pointed out in greater detail hereinafter. The roller 68a when it is depressed rides on a rail 68b which is positioned opposite a cam 43 on the latch 43 so that it positively engages the cam to move the latch to its position of Fig. 3.

The upper end of the sheath II is rigidly secured in the apparatus in its proper position with relation to the resistance conductor ID by means of a pair of jaws 69 which are mounted upon the plates I1 and 26. The two jaws 69 are mounted upon upright shafts III which have their upper ends mounted in a plate H and rigidly secured thereto by means of set screws 12.

Mounted on the lower ends of the shaftsll are gear members I3, which as shown, are secured to their respective jaw members '69 by means of screws 14 and pins 15. The gear-=mem-' bers 13 have intermeshing teeth whereby the jaws are caused to move together on'their axes. The plate II is roughly of T-shape and has a stem Ha extending downwardly, as shown in Figs. 15, 16, 17 and 18. Mounted within this stem function as an abutment for the upper end of the sheath II when the jaws are closed, as shown in Figs..14-18. The jaws below the inserts are pro- .vided with arcuate portions 69a which when-the jaws are closed'fit tightly about the upper end of the sheath, as shown in Figs. 15 and 16.

The plate II is secured to the plates IT and 26, and interposed between the plate II and the plate I! is a plate 19 also roughly of 'T-shape, and its stem 19a is fitted behind the stem Ila of the plate H, as shown in Figs. l5, 16, 17 and 18. The plates H and 19 are rigidly secured to the plates l1 and 26 by screw-fastening devices 88.

The jaws 69 are provided with over-center springs 8| which move them with a positive snap movement between fully opened and fully closed positions, the former being shown in dotted lines in Fi 18 while the latter are shown in full lines in this figure. The springs 8| are of the compression type and have their opposite ends bearing on collars 82 and 83 respectively. The collars 82 are provided with knife-edge seats 84 which receive knife-edge bearings 85 provided on the arms 86 attached to the jaw members, as clearly shown in Fig. 18. The opposite collars 83 are received in pivot bearings 81 which are rigidly mounted as shown in dotted lines Fig. 18. The members 88 came jaws project through apertures 92 pro- I vvided in the plates I1 and. 26, as shown in Figs. 9,

14 and 18, and the springs 8| and associated mechanism are located back of these plates, as shown in Figs. 2 and 18.

A suitable hopper 93 is mounted in an elevated position upon the frame I4 in any suitable way. This hopper discharges into a chute 94. The chute 94 discharges into a member 95 which i secured to the plate 25, as shown in Fig. 15. The

member 95 discharges into a passageway 95;

formed in the plates 26, I1, 19 and 1|, as clearly shown in Fig. 15. .The passageway 96 in turn discharges into the jaws directly above the open end of the sheath II, as clearly shown in Fig. 15. A suitable tongue-like cut-011 gate 91 is placed over the mouth of the passageway 96 to control the flow of'insulating-material to the sheath. The cut-off 91 at its upper end is connected to a cutoil actuating lever 98 (Figs. 1, 3, 9, 14 and 15), which is pivotally mounted upon the plate 19 by means of a screw-fastening device 99. The cut-off gate 91 is secured to the lever 98 by means of a block I (Fig. 15) which is rigidly secured to the cut-011: and which carries a pin l0I that is received in an elongated slot I02 provided for it in the lever. The pivotal movement of the lever 98 on the plate 19 is limited by a pin I03 mounted on the plates I1 and 26, as shown in Figs. 11, 14 and 15, and which is received inan arcuate slot I04 provided in the lever. The lever 98 is biased to move in a counter-clockwise direction, as viewed in Figs. 9 and 14, that is, in a direction to open the cut-off by means of a spring I05 which is secured at its lower end to the lever, as shown in Figs. 9 and 14, and at its other end is anchored to a pin I06 (Figs. 9, 11 and 12) which pin is fixed to the plates I1 and 25. The cut-off lever 98 is prevented from moving in its counterclockwise direction by means of a latch I010, which is pivotally mounted on a latch arm I01 by means of stud I011). The latch l01a may rotate in a counter-clockwise direction with respect to the arm I01, but is prevented from turning in a clockwise direction with respect to the arm by a ledge I010 on the arm I01. A spring I01d mounted on the arm I01 normally biases the latch N10. to its position shown in Fig. 9 where it abuts the ledge I010. The latch arm I01 is pivotally mounted on a pin I08 that is rigidly secured to the plates I1 and 26, and it is biased to move to its latching position, that is, is biased to move in the clockwise direction, as viewed in Fig. 9, by means of arm I09 (-Figs. 9 and 13) which has its right-hand end, as viewed in these figures, pivotally secured to the arm I01 above the pivot I08 of the arm, and at its lefthand end forms an abutment for one end of a compression spring IIO; the opposite end of this spring bears against a fixed abutment I I I so that the arm I09 and hence the arm I01 are biased to their latching positions. The abutment I I I, as shown in Figs. 9 and 13, is secured to a block II2 which in turn is secured to the plates I1 and lI3a. An openin in the block H2 serves as a uide for the leftand rod 54.

A guide member c for the rod 48 is also secured at the rear of plate 28 by the screw fastening device '3.

The latch arm I01 is moved to its unlatching position to permit the lever 98 to open the ieed gate 91, that is, is moved in the counter-clockwise directlon, by means of a control arm I which is pivotally mounted upon a plate II5 which is doweled to a block II5a, a spacer II5b i and the plates I1 and these members are fur- 30 by a screw fastening device H3 and dowels ther secured by means of a screw I I8. An opening in the block I I511 serves as a guide for righthand rod 54. The control arm H4 i connected to the latch arm I01 by means of a link II1 pivotally connected at one end to the lever Ill, as shown in Fig. 9, and at its opposite end to the latch arm I01. When 'the lever H4 is depressed, that is, is moved in the clockwise direction, as viewed in Fig. 9, it moves the latch arm I01 and hence the latch I01a to release the lever 98 and thereby permit it to move in the counterclockwise direction to open the insulating material cut-oil 91. The lever 98 is returned to its latched position to shut oif the flow of insulating material to the sheath by means of a cut-off cam II8 (Figs. 1, 3, 9, 14 and 15) which is mounted upon the carriage 52. This cam coacts with a roller I I8a on the lever 98.

g The carriage 52, the bridge 49, the rods 54 and the centering tube 48 attached to them are given a reciprocatory motion up and down with reference to the frame I4, the carriage sliding in the columns I5 and the bridge 49 sliding on the flange sections I9. This motion is imparted to these members by means of a shaft II9 (Fig. 10) which is rotatably mounted in a bearing I20 which in turn is mounted on the plates I1 and 26. The shaft II9 will be connected with any suitable constant speed drive, such as a constant speed motor (not shown) operating through a suitable gear train (not shown) interposed between the motor and the shaft. Secured to the inner end of the shaft H9 is a disc I2I which rotates in a circular recess provided for it in the bearing I20, as shown in Fig. 10. This member carries a crank pin I22 which functions to reciprocate a member I23. This member I23 is arranged to reciprocate in a path parallel to the plate I1. As shown in Figs. 6, '7, 8 and 10, the upper part of the member I23 is in the form of a channel which defines a relatively long U in cross-section. Beginning with a point indicated I24 in Figs. 9 and 10, the lower part of this member has an L-shape, as more clearly shown in Figs. 12 and 13. The upper part of the member I23 carries on its back surface a plate I25 (Figs. 4, 5 and 7) which is secured to the member I23 by means of rivets I26. This plate extends outwardly at the sides beyond the side edges of the member I23, and in these projecting portions are elongated vertically arranged slots I21. Shoulder screws I28 as shown on Figure 4 are passed through these slots and are received in threaded engagement in the plate I1. The heads of these screws are spaced slightly away from the plate I25 so that the plate has free sliding movement on the plate I1.

At the bottom, the member I23 is secured to the plates I1 and 26 for sliding movement by means of a headed bolt I29, as shown in Figs. 9, l0 and 12. As shown in Figs. 10 and 12, the member I23 at the bottom carries a block-like plate I30 and also an elongated vertically positioned plate I3I placed in front of the plate I30 as shown in Fig. 10. A cover plate I32 is positioned on the plate I3I. The plates I30, I3I and I32 are secured together and also to'the,

member I23 by means of screws I33 (Fig. 9).

The plate I30 has an elongated opening I30a which fits about a reduced part I34 which is free to rotate on the bolt I29, while the plate I3I has an elongated opening I35 in which the head (if the bolt I29 slides. It will be observed that by reason of this arrangement the plates I30,

I3I, I32, as well as the member I23, are secured to the walls I1 and 26 for sliding motion relative to them. A spacer plate I36 is placed between the back surface of the member I23 and the front surface of the plate I1.

A fixed pocket-like casing member I31 is placed around the lower ends of the assembly including the plates I30, I3I and I32 and the member I23, and is secured to the plate I1 in any suitable manner as-by means of screws I38 (Fi 12).

Also secured to the front face of the plate I3I above the plate I32 and having its lower end abutting the plate I32 is a sheet-like facing member I39. This may be secured to the plate I3I in any suitable manner, as by welding. Secured to the front surface of this facing member I39 at the top is a plate I40. This plate may be secured to the plates I3I and I39 in any suitable manner as by welding.

A crank arm I4I is pivotally connected at one end to the crank pin I22 and at its other end to a pin I42 which is secured to the plates I3I and I39 and also to the member I23 so that when the shaft I I9 is rotated the entire assem-- bly including the member I23 is reciprocated up and down.

The upper end of the plate I40 is spaced from the plate I43 which is positioned between the flanges of the member I23, as clearly shown in Fig. 10. The plate I43 is secured between these flanges by means of rivets I44. The plate I43 has a downwardly extending thinner section I43a, as shown, and between this section and the plate I40 is mounted a spur gear I45 and a ratchet wheel I46 which are secured together by means of pins, as shown in Fig. 10, and which are mounted to rotate upon a shaft I41 mounted on the plate I40. A pawl I48 is arranged to cooperate with the ratchet wheel I46. This pawl is rotatably mounted on a pawl arm I49 which is pivotally mounted on a bearing member I50 that is mounted in the plates I40 and I43, as clearly shown in Fig. 10. A spring-pressed plate I 53 may be adjusted, an also is provided with a lock nut I60.

Meshing with the-two gear wheels I45 and I52 is a continuous chain I6 I, the tension of which is adjusted by the screw I56. This chain is anchored to the bridge 49 and hence to the centering tube 48 bymeans of an anchor I62 secured to ends of the chain and which is received in a key-way I63 provided for it in a member I64. The member I64 is rigidly secured to a plate I65 which is riveted to the. carriage 49, as clearly shown in Figs. 4 and 6. 6

It will be observed in view of the foregoing construction that if the shaft I,I9 be rotated, the member I23 will be reciprocated up and down with a simple harmonic motion. And if the pawl I46.

be out of engagement with its ratchet wheel I46,

thereby permitting the spur gears I45 and I52 to ber I66 mounted on the upper end of the latch plunger I5I normally holds the pawl I48 from I23 and which is slidably-mounted therein for relative vertical adjustment with reference to it. Thisplate I53 is provided with an elongated slot I54 which receives a key I55 which is secured between the flanges of the member I23 by the rivets I26 which are utilized to secure the plate I25 to the member I23. The plate I53 at its lower end is in contact with an adjusting screw I56 which is threaded in a block I51 which is secured between the flanges of the member I23 by means of rivets I58. The screw is provided with a head I59 whereby it may be adjusted and hence whereby the position of the member I01, and which is positioned to engage an extension of the member I49, as shown in Fig. 9, t prevent engagement of the pawl until the latch is moved counter-clockwise, as viewed in this figure, to release the insulating material feed control lever 98 to permit insulating material to flow from its hopper. This movement of the latch, as pointed out previously, is controlled by the mem-' ber H4, and the pawl will be free to move into engagement with the ratchet until the member I I 4 is operated to return the latch I 01 to its latching position.

Suitable means are provided for applying to the sheath a plurality of intermittent impacting blows to settle the insulating material as it is fed to the sheath. For this purpose, a vibrator I 61 (Figs. 1 -and 2) is provided. The vibrator I61 comprises a straight plunger hammer I69 arranged to tap the sheath II, as shown in Fig. 1. The plunger hammer is rapidly reciprocated or vibrated and engages the side of the sheath with intermittent impacting blows. The plunger hammer I69 is driven by means of any suitable vibrating mechanism I10. The vibrating mechanism has not. been illustrated in detail for any suitable vibrating mechanism maybe used, and the details of this mechanism form no part of the present invention. The vibrator I61 is mounted upon asuitable bracket I1 I which in turn is secured to the bracket 23. The vibrator is controlled by means of a switch" and whichpreferably will be of the fluid type, such as a suitable mercury switch. The contacts in this switch are so arranged that when the control lever I I4 is in its position of Fig. 1, the vibrator will be'deenergized, whereas when the arm isdepressed to its position of Fig. 3, the mercury will complete a circuit through the switch I12 to energize the vibrator.

apparatus of this invention, it will be understood that the terminals I2 will be secured to the resistance conductor I0 in the manner previously described, and then the-sheath II will be slid up over the centralizer rod 48 until the jaws 35a of In making an electric heating unit using the terminal hook 35--.a re exposed. The relatively I12 mounted on the control lever II4,

small head 01' the upper terminal I2 will then be inserted in the hook 35 on the lower end of rod 34.

Then the eyelet 44!) will 'be pulled down so as to move the lever 33 from itsposition of F18. 3 to its position of Figs. 1 and'4 in which position it is held' by the latch 43. This operation elevates the rod 31 and thereby elevates the rod 34 and the. upper terminal I2, so as to pull the hook 35 up into the centralizer 45, thus preventing accidental unlocking of the terminal from the hook while the necessary operations required of handling the sheath II for the loading operation of insulating powder I3 are being made.

The sheath II then will be slid down over the heating element I and the lower terminal I2, which is provided with the washer or head 3|, will be received within the recess 32 previously referred to so as to close the lower end .01 the sheath H and also so as to anchor and center the lower terminal I2 with reference to the sheath. The lower end of the sheath will then be placed upon the base 23 so that the protuberance 33 on the base is received in the recess 32. Then the jaws 63 with inserts I3 will be closed about the upper end of the sheath to hold the sheath in its proper position in the apparatus. The overcenter springs 33 function to hold the jaws closed.

Then by means of the knob 53 the carriag 52 and all of the parts connected with it will be lowered from its position of Figs. 1 and 2 to its position of Fig. 3. Th s lowers the centralizing tube 43 down into the sheath to its dotted line position shown in Fig. 19. Preferably, a stop I13 will be fixed on one of the rods I5, as shown in Figs. 1, 2 and 3, which will be engaged by the lower edge of carriage 52 to limit the lower travel or the carriage and hence of the centralizing tube. The stop will be positioned so that when it is engaged by the carriage 52, the centralizer 45 will have a. small clearance from the head or washer 3I. When the carriage is depressed it carries with it the roller 63a which engages the latch 43 in the manner previously described to release the lever 33 and permit it to move to its initial position where it is again engaged by the latch as shown in Fig. 3. This permits the rod 34- and-terminal I2 to move back to their proper lower positions;

Then the lever 4 will be depressed from its position of Figs. 1 and 9 to its position of Fig. 3.

This operation will start the vibrator I61. It will' be understood that simultaneously. with this operation of the lever I I4 the power means driving the shaft II3 may be startedby any suitable switch (not shown), or that this power means may have been started previously. The latter is preferred.

and preferably the power means'will operate the' shaft II3 continuously during successive loading operations. Also when the lever II4is depressed it will actuate the latch I31 .to release the insulating material feed lever 33, which thereupon will move in the counterclockwise direction, as

viewed in the figures, to elevate the feed gate 31 to permit the insulating material to flow from the hopper 33 into the upper end of the sheath II. Also this operation of the latch will release the pawl-carrying member I43 to permit the pawl I43 to engage its ratchet wheel I46.

When the pawl I43 engages its ratchet wheel I46, the centralizer tube 43 will be oscillated up and down with the member I23, which member, as previously described, is reciprocated with a simple harmonic motion. Therefore, the centralizing tube as it is operated up and down will intermittently carry the centralizer 45 into engagement with the insulatingmaterial, the level of which is continuously rising in the sheath. The

resisted and it is temporarily released from the reciprocating member I23 by the slippage between the ratchet wheel I46 and the pawl I43.

The centralizer exerts some pressure on the insulating material each time it engages it, because the total weight of the carriage and its elements plus its momentum and also the pawl I48 resists somewhat the slippage it has with the ratchet I46 due to the weight of the pawl lever I43. This pressure displaces the insulating material both inside and outside the centralizer causing the displaced material to move upwardly. The upward movement of the insulating material inside the centralizer is facilitated by the inclined surface 41a. On each of the downward strokes of the centralizer, the insulating material climbs up the inclined surface to the desired level. This upward movement of the insulating material on the inside of the tube elevates slightly the turns of the resistance conductor. The force with which the centralizer tube thus displaces the insulatlng material and the inclination of the surface 41a are so controlled that the insulating material elevates the turns just enough to compensate for the sag of the turns due to their own weight and the weight of the settling material. This is particularly important due to the present trend of using heating elements of a large number of turns of light gauged wire and relatively large outside diameters, as this is a condition which causes-excessive sag.

Due to the fact that the centralizer intermitwisedireotion to depress the gate 31 to cut down the flow of insulating material to the sheath. The flow will be materially reduced by this operation and this reduction in the rate of flow is caused as the insulating level reaches approximately the lower end of the upper terminal II. The apparatus continues to fimction with the insulating material flowing in at the reduced rate until the sheath is loaded at .which time the inclined surface of the cam II3 engages the roller I In and causes the lever 33 to rotate to its original position to completely shut ofl the flow of powder to the sheath.

At this time, the wedge 53 will be engaged by the rollers 62 so that the wedge and the parts attached to it will be secured in their upper positions; it is to be understood that during the upward travel of the centering tube, the plate 63 will rest upon the bridge 43 and that after the wedge 53 has been engaged and held by the levers 63, the bridge 43 and its associated parts will drop downwardly from the plate 60 the limited distance permitted by the bolts 6|. This operation causes the centralizer to drop down to its dotted line position of Fig. 19 so that it will hold the upper terminal I2 from migrating off center due to transmitted vibrations. This operation also permits the cam H8 to drop away from the roller H8a. However, previous to this dropping away of the cam H8, the operating lever H4 will have been engaged by the pin Il ion the carriage 52 so as to have been operated from its position of Fig. 3 to its initial position of Fig. 1. This operation of the lever I I4 will have returned the latch arm I01 to its initial position to hold the lever 98 in its initial position regardless of the fact that the cam H8 has been withdrawn somewhat from the roller H8 a. The latch IOla is free to buckle to prevent possible damage due to a premature operation of the latch to its latching position.

Also, when the lever II 4 returns to its initial position to move the latch arm I01 to its initial position, the roller I66 carried -by the latch will engage the pawl-carrying member I49 so as to release the pawl I48 from the ratchet I 46. Also the lever Il i will operate the switch I12 to deenergize the vibrator I19.

It is to be. noted that the roller 68a will not have any efiect on the latch 43 when the centralizer tube rises because at this time the latch will be in its position of Fig. 3 and the cam 43f will be removed from the path'of the roller.

It will be understood that as the centralizing tube rises in the sheath during the filling operation the ribs 46 on the centralizer will slidably engage the inner walls of the sheath so as to hold the resistance coil I centrally within the sheath. Also, it will be understood that the insulating material can flow through the centralizer to the portions of the sheath under it through the spaces between the centralizer and the sheath and also down through the resistance coil.

Moreover, it will be understood that as the powder level rises during the loading operation and as it is acted on by the oscillating centralizer, the vibrator I61 is continuously functioning to settle the insulating material in the sheath as it is admitted to the sheath.

When the sheath has been loaded, to remove it from the machine the jaws are moved to their open positions. They are positively opened by means of their springs 8| and their open positions are limited by the stop plate 9I, as previously described. Then, the entire, heating unit may be elevated from its support 29 to' remove the head 33 of the upper terminal from the hook 35 and to withdraw the lower end of the sheath from the protuberance 30 on the support 29.

The apparatus is then in its initial condition ready for loading another heating unit.

If at any time it is desired to stop the operation of the machine before the sheath has been filled it is merely necessary to return the operating lever H4 to its position of Fig. 1. Here also, the latch IOIa can buckle so as to permit thecontrol arm to move to this position even though the lever 98 is in its feed gate open position. Also the powder flow can be stopped by rotating the power feed lever 98 clockwise.

Also it is to be noted that the spring-pressed plunger I5I engaging the pawl I48 is provided to permit slippage of the pawl in case of emergency. Fbr example, this emergency may occur due to the centralizer vanes 46 getting stuck in the sheath II due to either insuflicient clearance or particles getting wedged between these two elements.

Different lengths of sheaths within small limits may be filled with this apparatus by providing a resilient mounting for the head 29 which supthe head 29 on a plunger 290: which is received in the base 28 and which will be arranged in the form of a cylinder. Positioned within the cylinder and below the plunger 29a is a suitable compression spring 29b. I I

It will be understood that a single machine may be operated as has just been described to load the sheaths, or that a number of these machines may be arranged in a bank or battery, or arranged on a rotary platform so that the operator can work from a fixed position.

Important features 'of this invention are the provision of the means for positively driving the centralizing tube with a simple harmonic motion so that it intermittently engages the level or surface of the insulating material as it rises in the sheath. As previously pointed out, each time that the centralizer engages the insulating material it displaces the insulating material upwardly to eliminate sag of the conductor turns.

' Another important feature of this inventionis the insurance of uniform density of insulating material throughout the sheath. The reduction in-the rate of feed of the insulating material at the upper end of the sheath insures a more dense settling of the insulating material than would be the case if it flowed in at the same rate as in the lower portions of the sheath. This insulating ports the sheath. This may be done by mounting material flowing in at a slower rate is vibrated for a sufiiciently long period'of time to insure the same density at the top of the sheath as at the bottom. a

Furthermore, the slowing down of the feed at the top is of importance in that it is possible to control the height to which theinsulating material rises in the sheath and also permits the vibrator to pack thepowder at the top to a,

greater density than is the case without the powder flow slowing down. This height is ace curately controlled as one of the functions of the machine and the flow of insulating material is instantly shut off at the predetermined level.

The constant .vibratory hammering of the sheath by the vibrator and the controlled rise of the oscillating centralizing tube not only control the uniformity of the spacing of the turns of the winding but also insure a uniform'density in the insulating material.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be'made, and. I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention. f

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. Apparatus for loading granular insulating material into the sheath of a sheathwire heating unit that s provided with a sheath, and a coiled res stance conductor in said sheath which is embedded in and held in spaced relation with said sheath by said insulating material, comprising means for holding said sheath in an upright posiber is stopped by its engagement with said insulating material, and for automatically redriving it on its stroke to move said guide member away from said material so that said guide member forcibly and periodically engages said insulating material as it fills said sheath and progressively moves in said sheath toward said upper end as the amount of insulating material in said sheath increases, said guide member being provided at its lower end with a portion adjacent said conductor inclined upwardly and inwardly toward said conductor so that when it forcibly engages said insulating material it elevates the insulating material sufficiently to prevent the turns of said conductor from moving toward the lower end of said sheath due to their own weight and the weight of the insulating material fed in.

2. Apparatus for loading insulating material into the sheath of a sheathed heater having a helical resistance conductor in said sheath embedded in said insulating material, comprising means for holding said sheath in an upright position, means for continuously feeding said insulating material into the upper end of said sheath at a regulated rate, a guide member slidably mounted in said sheath around said conductor to hold said conductor from moving laterally in said sheath, a reciprocating driving member for said guide member, a ratchet wheel on said driving member, a yielding pawl on said driving member engaging said ratchet wheel with predetermined yielding force, and connection means between said ratchet wheel and said guide member for reciprocating said guide member when said pawl prevents said ratchet wheel from rotating, and said pawl yielding so that said ratchet wheel will rotate temporarily each time said guide member forcibly engages the insulating material in said sheath so that said driving member continues its movement to the end of its stroke independently of said guide member, whereby as the amount of material fed in the sheath increases said guide member is gradually and progressively moved upwardly in said sheath.

3. Apparatus for loading granular insulating material into a sheathed heater of the type having an outer sheath and a helical resistance conductor in said sheath embedded in the granular resistance material, comprising means for holding said sheath in an upright position, means for feeding said granular insulating material into the upper end of said sheath at a regulated rate, a guide member slidably mounted in. said sheath around said conductor to hold said conductor from moving laterally in said sheath, a driving member for said guide member, means mounting said driving member for vertical reciprocating motion, a pair of vertically-spaced rotatable members mounted for free motion on said driving member, a belt mounted on said rotatable members, means attaching said belt to said guide member, and means for connecting said belt to said driving member so that guide member is elevated and depressed in said sheath by said driving member as it reciprocates, said connecting means being constructed and arranged to temporarily release said belt from said guide member on the downward stroke of said driving member upon the exertion of predetermined resistance to the downward motion of said guide member by said insulating material.

4. Apparatus for loading granular insulating material into the sheath of a sheathed heater having a helical resistance conductor in said sheath embedded in the granular resistance material, comprising means for holding said sheath in an upright position, means for feeding said granular insulating material into the upper end of said sheath at a regulated rate, a guide member slidably mounted "in said sheath around said conductor to hold said conductor from moving laterally in said sheath, a driving member for said guide member, means mounting said driving member for vertical reciprocating motion, a pair of vertically-spaced gears on said driving member mounted for free rotation on fixed axes, an

endless chain mounted on said gears intermeshed with the teeth thereon, means attaching said chain to said guide member, a ratchet wheel attached to one-0f said gears so as to rotate with it, and a pawl carried by said driving member arranged to engage said ratchet wheel to prevent rotationthereof except when the motion of said guide member downwardly in said sheath is resisted by its engagement with said insulating material.

5. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit provided with a resistance conductor in said sheath embedded in and supported in spaced relation to said sheath by said insulating material, comprising a vertical frame, means for supporting the sheath in an upright position in said frame, means for continuously delivering said insulating material into the upper end of said sheath, a carriage mounted on said frame for vertical movement therein, a guide attached to said carriage so as to move with it and constructed and arranged to be mounted in and moved vertically in said sheath to prevent substantially lateral movement of said resistance conductor in said sheath while said insulating material is being fed in, a driving member mounted in said frame for vertical reciprocating motion, means for continuously reciprocating said driving member, and a driving connection between said driving member and carriage for reciprocating said carriage and thereby reciprocating said guide up and down in said sheath including means for temporarily releasing said carriage from said driving member when said insulating material resists the downward motion of said guide so-that said driving member can continue its downward stroke independently of said guide.

6. Apparatus for loading granular insulatin material into the sheath of a sheath wire heating unit provided with a resistance conductor in said sheath embedded in and supported in spaced relation to the sheath by said insulating material, comprising means for holding said sheath in an upright position, means for continuously feeding said insulating material into the upper end of said sheath, a guide for said resistance conductor slidably mounted in said sheath and constructed and arranged to hold said conductor from substantial lateral movement in said sheath while said insulating material is being loaded, a reciprocating driving member having a fixed operating stroke, a driving connection between said driving member and said guide constructed and arranged to forcibly drive said guideup and down in said sheath and to release said guide temporarily upon a predetermined resistance to its downward movement by its engagement with said insulating material so that said driving member may complete its downward stroke independently of said guide, the driving connection being reestablished on the next upward stroke of said driving member so that said guide is reciprocated up and down in said sheath and is asraose gradually elevated therein as said insulating material is fed in, and means releasing said driving connection when said guide has been elevated a predetermined distance.

7. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit provided with a resistance conductor in said sheath embedded in and supported in spaced relation to the sheath by said insulating material, comprising means for holding said sheath in an upright position, means ior continuously ieeding said insulating material into the upper end of said sheath, a guide for said resistance conductor slid'ably mounted in said sheath and constructed and arranged to hold said conductor from substantial lateral movement in said sheath, a reciprocating driving member having a fixed operating stroke, a driving connection between said driving member and said guide constructed and arranged to forcibly drive said guide up and down in said sheath and to release said guide temporarily upon a predetermined resistance to its downward movement by the engagement of said guide with said insulating material so that said driving member can complete its downward stroke independently of said guide, the driving connection being reestablished on the next upward stroke of said driving member so that said guide is reciprocated up and down in said sheath and is gradually elevated therein as the level of said insulating material rises, and means for releasing said driving connection and for stopping the flow of insulating material to said sheath when said guide has been elevated a predetermined distance.

8. Apparatus for loading granular insulating material into the sheath of a sheathed heater having a helical resistance conductor in said sheath embedded in the granular resistance material, comprising means for holding said sheath.

in an upright position, means for feeding said granular insulating material into the upper end of said sheath at a regulated rate, a guide slidably mounted in said sheath around said conductor to hold said conductor from substantial lateral movement in said sheath, a reciprocating driving member for said guide, a driving connection between said driving member and said guide for moving said guide up and down-in said sheath including a ratchet wheel mounted on said driving member, a pawl mounted on said driving member for engaging said ratchet wheel to prevent its rotation, means connecting said ratchet wheel with said guide so that when the wheel is locked against rotation said guide is driven by said driving member and when it is released said driving member operates independently of said guide, the pawl automatically releasing said ratchet wheel upon the occurrence of a force predetermined magnitude resisting the downward motion of said guide so that said guide is progressively elevated as the level of insulating material rises in said sheath, a lever controlling the movement of said pawl into and out of engagement with said ratchet wheel, means automatically operating said lever to move said pawl out of engagement with said ratchet wheel when said guide has been elevated a predetermined distance, and means operated by said lever for cutting oil the flow of insulating material to said sheath when said lever moves said pawl out of engagement with said ratchet wheel.

9. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit provided with a resistance conductor in said lation with the sheath by said insulating material, comprising means ior supporting said sheath in an upright position, a grasping member for grasping and holding the upper end of said conductor, a tubular guide member slidably mounted in said sheath to hold said resistance element in spaced-relation to said sheath, and

when moved down into said sheath surrounding said grasping member, said guide member being movable upwardly to a position to expose said grasping member when said grasping member is in its position for attachment with said upper end of said resistance conductor, means for elevating said grasping member up into said guide member, and means operated responsively to the movement of said guide member down into said sheath for returning said grasping member to said position.

10. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit provided with a resistance conductor in said sheath and embedded in and supported in spaced relation with the sheath by said compacted insulating material, the resistance conductor being connected at its ends to terminals mounted in the ends of said sheath, comprising means for supporting said sheath in an upright position, a grasping member for grasping and holding one of said terminals, a tubular centering device mounted for movement in said sheath to hold said resistance element centrally of said sheath, and when moved down into said sheath surrounding said grasping member, said centering device being movable upwardly to a position to expose said grasping member when said grasping mem her is in its position for attachment with said one terminal, a member attached to said grasping member for moving it from said position up into said centering member after said terminal has been attached, means biasing said grasping member toward said position, a latch for holding it up in said centering device, and a cam attached to said centering device for operating said latch to release said grasping member when the centering device is lowered into said sheath to thereby permit it to return to said position.

11. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit provided with a resistance conductor in said sheath embedded in and supported by said insulating material, comprising means for holding said sheath in an upright position, feeding means for delivering said insulating material into the upper end of said sheath so as to fill the sheath from the bottom to the top, a movably mounted control member, means operated by said control member when the latter is moved to a first posisheath embedded in and supported in spaced retion for controlling said feeding means to reduce the rate of feed of said insulating material into said sheath and when moved to a second position for controlling said feeding means to shut off the feed of said insulating material to said sheath, and means engaging the surface of the insulating material in said sheath for operating said control member to said first position when said insulating material attains a predetermined height in said sheath, and to said second position when said insulating material reaches substantially the upper end of said sheath.

12. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit provided with a resistance conductor in said sheath embedded in and supported in spaced relation to the sheath by said insulating material, comprising means for holding said sheath in an upright position, a delivery member for directing said insulating material into the upper end of said sheath, a gate controlling the flow from said member to said sheath, a lever for operating said gate between opened and closed positions, means biasing said lever to open said gate, manually releasable means holding said lever in its position to close said gate against the force of said biasing means, a cam cooperating with said lever constructed and arranged when moved to a first position to operate said lever to partially close said gate thereby to cut down the rate of flow of said insulating material into said sheath and when moved to a second position to operate said lever to shut said gate to stop the flow of said insulating material to said sheath, and means operated by said insulating material as its level in said sheath rises for operating said cam to said first position when said level attains a predetermined height in said ,sheath and to said second position when said level rises substantially to the upper end of said sheath.

13. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit that is provided with a sheath, and a coiled resistance conductor in said sheath which is embedded in and held in spaced relation with said sheath by said insulating material, comprising means for holding said sheath in an upright position, means for feeding said insulating material into the upper end of said sheath, a guide member slidablymounted in said sheath provided with a section around said resistance conductor so as to hold it from substantial lateral movement in said sheath while the sheath is being filled, means for effecting up and down movements of said guide member in said sheath so that the lower end of said section periodically engages said insulating material as it fills said sheath, said lower end being provided with a tapered wall inclined upwardly and inwardly toward said conductor so that when it engages said insulating material it elevates the insulating material about said turns sufiiciently to prevent said turns from moving toward the lower end of said sheath due to their own weight and the weight of the insulating material fed in.

14. Apparatus for loading sheath wire heating units provided with a sheath, a resistance conductor in said sheath and granulated insulating material within said sheath embedding said resistance conductor to hold it in spaced relation with said sheath, comprising a support for the lower end of said sheath upon which said sheath can be placed in an upright position, and a plurality of jaws arranged to clamp the upper end of said sheath, said jaws being provided with sections defining sheath abutments over the upper end of said sheath when the jaws are closed, and also having sections above the sheath which when the jaws are closed define a passageway for guiding the insulating material to the upper end of said sheath.

15. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit provided with a resistance conductor in said sheath embedded in and supported in spaced relation with the sheath by said insulating material, comprising a support for the lower end of said sheath upon which said sheath can be placed in an upright position, a plurality of jaws arranged to clamp the upper end of said sheath, means pivotally mounting said jaws for movement to closed positions to clamp said sheath and to open positions .to release said sheath, a driving connection between said jaws, and over-center spring means connected with said jaws to move them positively to their closed and opened positions.

16. Apparatus for loading sheath wire heating units provided with a sheath, a resistance conductor in said sheath and granulated insulating material within said sheath embedding said resistance conductor to hold it in spaced relation with said sheath, comprising a frame, means for holding said sheath in an upright position in said frame, feeding means for delivering said insulating material to the upper end of saidsheath, a centralizing tube slidably mounted in said sheath to centralize said resistance conductor, a carriage slidably mounted in said frame for vertical movement therein, means securing said tube to said carriage, a plate mounted in said frame for vertical movement therein, means for reciprocating said plate through a fixed stroke, connection means between said plate and said carriage for positively elevating said carriage and centering tube when said plate moves up and for lowering said carriage and centering tube when said plate moves down and constructed and arranged to release said carriage temporarily when the downward movement of said centering tube is resisted by the insulating material in said sheath so that the plate can continue its downward movement to the lower end of its stroke and to reestablish the driving connection for movement by said plate when it returns to the upper limit of its stroke, whereby said tube is reciprocated in said sheath and the lower limit of itsmovement is progressively elevated in said sheath, a manually operable device for operating said connection means to connect said carriage with said plate, and for operating said feeding means to start the flow of insulating material to said sheath, means operated by said carriage as it is elevated for controlling said feeding means to shut off the flow of insulating material to said sheath, and.

frame, feeding means for delivering said insulating material to the upper end of said sheath, a centralizing tube slidably mounted in said sheath to centralize said resistance conductor, a carria gm slidably mounted in said frame for vertical movement therein, means securing said tube to said carriage, a plate mounted in said frame for vertical movement therein, means for reciprocating said plate through a fixed stroke, connection means between said plate and said carriage for positively elevating said carriage and centering tube when said plate moves up and for lowering said carriage and centering tube when said plate moves down and constructed and arranged to re lease said carriage temporarily when the downward movement of said centering tube is resisted by the insulating material in said sheath so that the plate can continue its downward movement to the lower end of its stroke and to, reestablish the driving connection for movement by said plate when it returns to the'upper limit of its stroke, whereby said tube is reciprocated in said sheath and the lower limit of its movement is progressively elevated in said sheath, a manually operis being filled with said insulating material, said able device for operating said connection means to connect said carriage with said plate, and for operating said feeding means to start the flow of insulating material to said sheath, means operated by said carriage as it is elevated for controlling said feeding means to cut down the rate of flow of said insulating material to said sheath when the level of insulating material in said sheath reaches a predetermined height and for shutting off the flow completely when said sheath is filled, and means operated by said carriage for operating said connection means to disconnect said plate from said carriage.

18. Apparatus for loading sheath wire heating units provided with a sheath, a resistance conductor in said sheath and granulated insulating material within said sheath embedding said resistance conductor to hold it in spaced relation with said sheath, comprising a frame, means for holding said sheath in an upright position in said frame, feeding means for delivering said insulating material to the upper end of said sheath, a centralizing tube slidably mounted in said sheath to centralize said resistance conductor, a carriage slidably mounted in said frame for vertical movement therein, means securing said tube to said carriage, a plate mounted in said frame for vertical movement therein, means for reciprocating said plate through a fixed stroke, connection means between said plate and said carriage for positively elevating said carriage and centering tube when said plate moves up and for lowering said carriage and centering tube when said plate moves down and constructed and arranged to release said carriage temporarily when the downward movement of said centering tube is resisted by the insulating material in said sheath so that the plate can continue its downward movement to the lower end of its stroke and to-reestablish the,

driving connection for movement by said plate when it returns to the upper limit of its stroke, whereby said tube is reciprocated in said sheath and the lower limit of its movement is progressively elevated in said sheath, a manually operable device for operating said connection means to connect said carriage with said plate, and for operating said feeding means to start the flow of insulating material to said sheath, means operated by said carriage as it is elevated for con trolling said feeding means to shut off the flow of insulating material to said sheath, means operated by said carriage for operating said connection means to disconnect said plate from said carriage, and yieldable means for holding said carriage in its upper position, said means being i manually releasable to permit said carriage to be lowered.

19. Apparatus for loading sheath wire heating units provided with a sheath, a coiled resistance conductor in said sheath and granulated insulating material within said sheath embedding said resistance conductor to hold it in spaced relation with said sheath, comprising means for supporting said sheath in an upright position, means for feeding said insulating material into the upper end of said sheath, a tubular guide member slidably mounted in said sheath and constructed and arranged to hold said resistance conductor in fixed spaced relation with said sheath, and reciprocating driving means for said guide member for reciprocating it in said sheath as the sheath driving means being constructed and arranged to release said guide member temporarily when the motion of said guide member is stopped by the engagement of its lower end with said insulating material and the pressure of said guide member on said insulating material, exceeds a predetermined value, and for automatically reengaging it on its stroke to move said guide member away from said material sothat the guide member forcibly and periodically engages the insulating material as it fills said sheath, and the lower end of the inner wall portion of said guide member being inclined upwardly and inwardly toward said conductor, the pressure exerted on said insulating material when said guide member forcibly engages it forcing said material up said inclined surface to prevent the turns of said conductor from sagging downwardly in said sheath. 20. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit that is provided with a sheath, and a coiled resistance conductor in said sheath which is embedded in and held in spaced'relation with said sheath by said insulating material, comprising means for holding said sheath in an upright position, means for feeding said insulating material into the upper end of said sheath, a guide member slidably mounted in said sheath provided with a tubular section surrounding said resistance conductor so as to hold it from substantial lateral movement in said sheath while material as it fills said sheath, said lower end being provided with a substantially fiat walland a second wall inclined upwardly and inwardly therefrom toward said conductor, said walls when forced into contact with said insulating material elevating said insulating material around the turns of said conductor sufliciently to prevent the turns from moving toward the lower end of said sheath due to their own weight and the weight of the insulating material fed in.

21. Apparatus for loading granular insulating material into the sheath of a sheath wire heating unit that is provided with a sheath, and a coiled resistance conductor in said sheath which is embedded in and held in spaced relation with said sheath by said insulating material, comprising means for holding said sheath in an upright position, means for feeding said insulating material into the upper end of said sheath, a guide member slidably mounted in said sheath provided with a section around said resistance conductor so as to hold it from substantial lateral movement in said sheath while said sheath is being filled, means for effecting up and down movements of said guide member in said sheath so that the lower end or said section periodically engages said insulating material as it fills said sheath, said lower end being provided with walls positioned at an angle to each other so that when they engage said insulating material they elevate the material about said turns sumciently tolprevent said turns from moving toward the lower end of said sheath due to their own weight and the weight of the insulating material fed in.

, JOHN LEWIS ANDREWS. 

